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Take-off visibility/crosswind

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Hi there allJust looking at LHR weather - it is very foggy indeed. I was wondering if anyone knew what the minimum take-off RVR/visibility is for the 744 (I realise it may vary between companies), and I imagine the crosswind limits and the like would change too?Thanks for any helpRudy


Rudy Fidao

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150m is the absolute mimimum for any aircraft. Might be more fora heavy but I cannot remember from my comm test! Do not fly these things ;)FRED

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Depends on a number of factors including company policy. At one extreme, Alaska Airlines has heads up displays to allow departures at KSEA with CATIII minimums. Most major airports have a set of minimums published in the terminal procedures. In general, a Part 121 commercial operator needs at least landing minima in the event they need to return to the airport. Part 91 operators (GA) do not have departure minima regardless of aircraft type.


Dan Downs KCRP

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Guest db76

In regards to last post, not entirely correct. Part 121 operators do not need landing minima for departure. If taking off when the WX is below the approach minimums, then a takeoff alternate is required. This takeoff alternate must be within 1 hour of normal cruise speed with one engine inoperative, in still air.The actual amount of visibility required depends on airline ops specs, and a few other things. Most airlines can perform takeoffs when the RVR on the runway is "6,6,6" (600' touchdown, midfield, rollout), some to "5,5,5." But this is only possible, no matter what, if the runway itself is authorized for these types of departures. This info is found on the back of the airport diagram on Jepp plates. Requirements for the runway include centerline lights a visible center line (i.e. you can see the paint).Take care.David

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>150m is the absolute mimimum for any aircraft. Not true.Michael J.


Michael J.

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Gents,I have no numbers for you, only some thoughts about low vis ops.From what I understand from low visibility ops is that landing and departing is not the big problem. It's ground movement. You can land at zero visibility but you are stuck at the runway as you don't have any visibility to get off it. Same thing for take off. How are you getting to the runway if you don't see the taxiways? And if you don't see the taxiways you will most liekly not see the runway either making it hard to keep centre line during takeoff roll.Cheers,


Mats Johansson
PMDG Flight Test Dept
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>will most liekly not see the runway either making it hard to>keep centre line during takeoff roll.Believe or not such 'blind' takeoff is allowed when you fly according to Part 91 in US (most GA) - at least in piston aircraft - I am not sure about the heavier jets though. I was practicing such blind takeoff with my instructor - I was watching the heading on the gyro (I was under the hood) but I hated it - I would never attempt to do such a thing for real. I am amazed it is legal.Michael J.


Michael J.

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Yes, its 150 meters at LHR takeoff minima,for a less well equiped runway which doesn`t have centre line lights for example the minima goes up.There isn`t a x wind limit for the take off in low viz, but there are autoland limits 25 or 15 kts depending where in the world you arecheersJon

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JAR OPS Rules within EU:Daytime - No runway facilities = 500 meter RVRNight/Day - Edge lights or Centerline markings = 300 MetersNight/Day - Edgelights and CLL lights = 250 MetersNight/Day - Same but with RVR for whole takeoff area = 200 MetersThis was for CAT D/E AircraftCAT A/B/C can takeoff in 50 meters lower RVR except for a runway with no facilities where 500 Meter is the lowest permissable and only t/o permissable in daytime.So the lowest permissable for CAT A/B/C is 150 Meters when CLL lights and edge lights are available (and on) and the whole takoff run does not go under 150 meters RVR (= multiple RVR readings)Best,Bjorn

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